Ukip is emerging as the chief beneficiary of a mood of disillusionment with the EU, according to a new Guardian/ICM poll that records a surge for the party of two percentage points.

As David Cameron told the European commission it should stop "picking the pockets" of European citizens after it tabled an above-inflation increase in the EU budget prior to a summit this week, the poll found Ukip's share of the vote had increased to 7% since October.

Support for all three main parties fell back a point compared with the previous month leaving Labour on 40%, the Conservatives on 32% and the Liberal Democrats on 13%. The combined total of the assorted minor parties rose three points, to 15%, a score that has never been bettered in the 28-year history of the Guardian/ICM series.

The growing support for Ukip, which is committed to withdrawing from the EU, follows a poll over the weekend that found 56% of voters would probably or definitely vote to leave the EU if an in/out referendum were held. The Opinium/Observer poll found that 68% of Tory voters wanted to leave the EU.

The ICM poll came as the prime minister made clear that he would press hard for an inflation freeze in the next seven-year EU budget, due to run from 2014-2020, which will be the subject of the European summit in Brussels.

Cameron told the CBI annual conference: "I don't think it makes you a bad European because you want a tough budget settlement in Europe. I think it makes you a good European. I think I have got the people of Europe on my side in arguing that we should stop picking their pockets and spending more and more money through the EU budget, particularly when so many parts of the European budget are not well spent."

The prime minister said he was focusing on the planned €63bn (£51bn) budget for the EU's running costs over the seven years. He said: "One of the interesting things about the proposals so far in this debate about the EU budget is how little attention there has been on the central costs of the EU, the commission budget, what people get paid."

Herman Van Rompuy, the president of the European council, who met EU Europe ministers in Brussels on Monday night, has proposed cutting the administration budget by €1bn over the seven years. This is part of his proposal to cut €81bn from the original European Commission proposal to take the budget down to €973bn minus emergency "off-budget" spending.

The Van Rompuy proposal is designed to allow Cameron to declare that he has achieved a real-terms cut of €20bn – going further than his demand for an inflation freeze – on the EU's last seven-year budget, which runs from 2007 to 2013. One British source said: "We think this is good because it is a downward trajectory. But it does not go far enough."

The prime minister moved to show that he is serious about cutting a deal at the summit by holding telephone talks over the weekend with counterparts from Poland, Sweden, Denmark, France, Germany and the Netherlands. The prime minister's spokeswoman said: "He is working constructively to find a deal."

But Cameron was given a taste of the divisions within the Conservative party when the pro-European Kenneth Clarke confirmed he had sought an assurance from the prime minister that he did not intend to leave the EU. The former chancellor told the Today programme, on BBC Radio 4: "David Cameron assures the public, he has always assured me, that he believes, as I do, that Britain's place in the modern world has got to be in the EU."

Clarke, who warned it would be a "disaster" for Britain to leave the EU, spoke shortly before the former shadow home secretary, David Davis, said that "radical, out-of-Europe options" were becoming more attractive. Davis said the prospect of British withdrawal should concentrate the minds of EU partners under his plans for two referendums – one to agree a negotiating mandate in which Britain would opt out of key EU laws, and a second to approve a deal negotiated with the rest of the EU.

In his speech to the CBI, the Labour leader, Ed Miliband, warned the prime minister was in danger of forcing the UK out of the EU by accident. But the Labour leader said the EU must reform, as he acknowledged that Eurosceptics have often been right in their criticisms of Brussels.

Patrick Diamond, a close ally of Peter Mandelson's, who co-wrote Labour's manifesto for the most recent election with Miliband, praised him for demanding reform of the EU. But in a Guardian article, Diamond questioned Miliband's decision to vote with Tory Eurosceptics in favour of a below-inflation cut in the EU budget.

"Labour must not appear detached and inward-looking: putting Europe in the 'too difficult' box and isolating the party from European and international commitments which are integral to an effective social democratic strategy would be a grave error," Diamond wrote.

• This article was amended on 20 November 2012. The original said 56% of voters would probably or definitely vote to leave the UK if a referendum were held. That has been corrected to say they would vote to leave the EU.